To remove corrosion, rust, slag, paint, or coatings from a substrate such as a surface to be restored, painted, or cleaned, an abrasive blasting system is both desirable and necessary. In certain applications, abrasive blasting systems should be able to clean or remove corrosion, rust, slag, paint, or coatings without damaging the underlying metal or other substrate. In other applications, a certain degree of surface roughening (called profile) may be desired to assure new paint or coating adhesion.
The use of dry, hard abrasives, such as those used in conventional sand blasting, may result in excessive surface roughness to the point of causing damage to the substrate. Typical blast particles are hard (2.8˜9 on Mohs Scale of Mineral Hardness) and abrasive in order to increase the efficiency of the blasting operation. Soft blast particles (generally less than 2 on the Mohs scale), such as agricultural products which can include crushed walnut shells, rice hulls, corn cob, and pistachio shells, plastic or glass particles are sometimes used to reduce substrate surface damage.
Wet-abrasive systems have been used to control the generation of dust and minimize surface damage, even while using hard abrasives. Wet-abrasive systems rely on a method to force a slurry of the abrasive media into the compressed air-stream in a controlled manner. A blast pot or pressure vessel is charged with a liquid, typically water, and the solid abrasive to form the slurry. The blast pot is then purged of air, sealed, and connected to a source of pressurized water. The flow of pressurized water forces the slurry out of the blast pot, through a slurry piping system, and into a mixer. Also connected to the mixer is a source of pressurized gas, typically air. In the typical case, the water and abrasive slurry is mixed with the compressed air to form a three phase blasting stream of abrasive, water and air and directed through the blast hose and directed with the blast nozzle to the surface. Fluctuations in flow or pressure in either the slurry or pressurized gas at the mixer will provide inconsistent behavior of the wet abrasive blasting system and an inefficient blasting process.
There exists a need for a wet abrasive blasting system with increased consistency in pressure and flow at the mixer and ultimately at the blasting nozzle.